This invention is in the field of fluoropolymers. More particularly this invention relates to fluorine containing copolymers and barrier films made therefrom.
Monomers such as tetrafluoroethylene and chlorotrifluoroethylene have been used to make homopolymers and copolymers. Typical copolymers based on tetrafluoroethylene or chlorotrifluoroethylene are disclosed in U.S. Pat. Nos. 3,624,250; 4,123,602; 3,642,742; 4,513,129; and 3,847,881, and P.D. File 82-2155. U.S. Pat. No. 4,434,273 discloses perfluorovinyl ethers and copolymers of such materials with tetrafluoroethylene. U.S. Pat. Nos. 4,471,076 and 4,500,739 disclose fluorocarbon polymers containing carboxyl groups. U.S. Pat. No. 4,513,129 discloses copolymers of ethylene, tetrafluoroethylene or chlorotrifluoroethylene and fluorovinyl compounds of the formula H.sub.2 C.dbd.CFR.sub.f where R.sub.f is fluoroalkyl group of C.sub.2 -C.sub.10.
Improved barrier resistance of ethylene vinyl alcohol copolymers is disclosed in U.S. Pat. No. 4,427,825 and the Background of the Invention thereof, as well as related U.S. Pat. No. 4,468,427.
The above review of the art shows a great variety of fluoropolymers and copolymers. Modena, et al. Vinyl acetate and Vinyl Alcohol Copolymers with Tetrafluoroethylene, European Polymer Journal, 1967. Vol. 3, pp.5-12, Pergamon Press Limited, England (1967) discloses a specific class of copolymers of vinyl acetate and vinyl alcohols. Copolymers of tetrafluoroethylene and vinyl acetate are disclosed in Great Britain Patent 583,482 and U.S. Pat. No. 2,468,664. The Great Britain and U.S. patents disclose copolymers of tetrafluoroethylene and vinyl acetate but do not disclose polymers of tetrafluoroethylene with vinyl alcohol nor is there a recognition in any of these disclosures of improved barrier resistance to gases such as oxygen and that the fluorinated and vinyl units are distributed along the copolymer chain in a substantially alternating fashion.